Abstract: We investigated the impact of convexity and isoperimetric deficits on the accuracy of sectional area estimates of tree stems using traditional methods (caliper, tape, formulas based on stem diameter and circumference). In two complementary experiments, the use of photographs to estimate cross-sectional areas was first validated, then the use of a caliper and diameter tape was computer-simulated. The results indicated that the photographic method offers high precision, with mean relative errors below 0.1%, minimal deviation, and no significant bias, and the traditional methods led to substantial and systematic errors, with deviations from circularity and convexity significantly increasing the errors in area estimation.

Key words: Tree cross-sectional area measurement, Isoperimetric deficit, Convexity deficit, Photographic estimation, Forest mensuration, Stem geometry, Error analysis